Despite the observation that the proposal, as with other dividend proposals, would make shareholders poorer, that doesn't mean there isn't a very interesting point hidden in there.

Mention is made of the Accumulated Earnings Tax, a little known risk which perhaps should not have been ignored by Berkshire shareholders all these years. Since 1921, it appears.

A quick backgrounder here.
thetaxadviser.com - Resurgence of accumulated earnings tax

TL;DR
It's a one time tax on 20% of "excess" accumulated earnings, earnings retained beyond the needs of the business. It's phrased as a penalty for trying to let shareholders dodge their dividend tax, so it does not give rise to any offsetting future credit. So the pile would ultimately be subject to triple taxation if ever paid out as dividends in future. Sounds the existence of the pile is itself evidence of trying to dodge tax unless the company documented contemporaneously another specific need for the money. A secondary act that might demonstrate attempted tax dodging is deploying the excess retained earnings into investments unrelated to the business.

On the surface of things, either Berkshire is indeed liable for this tax but it hasn't been invoked because it's a regulation that almost never is, or plainly a regulator *could* adjudicate that they were. (Especially if the company or its boss were ever deemed to be an enemy of the people, of course, but let's not go there). Indeed, from that brief article, it seems to me pretty cut and dried if some ambitious tax agent tried to levy it against Berkshire, and I doubt a tax appeal would work.

Jim